1. Field of the Invention
The present invention pertains to retractable covers for storage facilities and more particularly to a telescoping cover having self-cleaning guideways on which it is designed to reciprocate.
2. Description of the Prior Art
Storage facilities may take many different forms, including vehicular cargo beds and stationary material containment structures. Tops designed to cover such storage facilities generally serve the purposes of providing security against entry by both the weather elements and unauthorized persons. The user, however, must be able to efficiently access the interior of the storage facility; thus, any provision for security must also take into account easy access. In addition, the special case of vehicular employment is particularly sensitive to the effects of wind when traveling at moderate to high speed, and provision must accordingly be made to ensure that integrity of seal between the top and the side walls is retained.
Several solutions have been advanced in the prior art which are directed to solving the particularly demanding conditions encountered in vehicular applications. These have generally two rather broad classes of approach: articulating covers, and retractable covers.
Articulating covers are generally composed of a plurality of segments which are designed to hinge upwards, thereby providing access to the interior of the storage area. U.S. Pat. No. 4,615,557 to Robinson discloses a panel cover having two sections which hinge transversely across the bed of a pickup truck and seat on a channel provided along the wall periphery. U.S. Pat. No. 4,313,636 to Deeds discloses a multiple segmented cover transversely hinged across a pickup truck bed, folding forwardly in the bed on an angle iron track. U.S. Pat. No. 4,284,303 to Hather discloses a two piece top which folds longitudinally along the pickup truck bed using hinged sections on the top of the side walls. All of these solutions require the user to lift a relatively large, unwieldy cover section which could in the process be very difficult under conditions of high wind.
Retractable covers are generally composed of segments which slidably move in relation to the storage facility, thereby permitting access to the interior of the storage area. Generally, these employ three types of methods that utilize either removable segments, accordion folding segments, or fan folding segments. Further, these generally employ a channel of either a "C" or "U" shape which is secured to the longitudinal side walls of the storage facility, which cooperate with a lip at either end of the longitudinal sides of the cover segments to permit slidable movement in the longitudinal direction while preventing movement in the transverse and vertical directions.
The removable segment solution is disclosed in U.S. Pat. No. 4,406,493 to Albrecht et al which describes a modular hard top for pickup truck beds, each component of which is slidably secured to the side walls via a "C" shaped channel cooperating with top segment lips.
The accordion folding solution is disclosed in U.S. Pat. No. 4,547,014 to Wicker which describes a generally "C" shaped channel mounted longitudinally on the side walls of a pickup truck which accepts for slidable movement therein a series of transverse cross members supporting a "C" shaped channel secured to the side walls of a pickup truck cooperating with a series of guides slidably moving therein to fold a bow structure supporting a flexible top material using a crank.
The fan-folding solution is disclosed in U.S. Pat. No. 4,611,848 to Romano which describes a "C" shaped channel mounted interiorly at the top of a pickup truck's side walls. A series of transverse cross members are movably supported by wheels located in the channels thereby allowing stiff cover panels to be crankably rolled onto a rewind tube. U.S. Pat. No. 4,550,945 to Englehardt describes a fan-folding segmented panel cover which rests on a pickup truck's side walls, utilizing pins for retention thereon. U.S. Pat. No. 4,518,194 to Kirkham et al describes use of "C" shaped channel designed to slidably cooperate with hinged slide bars supporting a plurality of segmented rigid cover panels, permitting folding of the panels forwardly in the bed by means of a motor actuating crank. U.S. Pat. No. 4,273,377 to Alexander describes use of a "U" shaped track located interiorly at the top side walls of a pickup truck which has a pair of grooves serving as guides for ball bearings that are integral on a bearing guide which support in turn a plurality of transverse support members. U.S. Pat. No. 4,252,362 to Campbell describes use of generally "C" shaped channels mounted to the interior side walls of a pickup truck in which are located a plurality of wheels that support, at each end, cross members which in turn support a flexible top material; the channel is designed to permit various amounts of the bed to be closeably covered.
U.S. Pat. No. 4,289,346 to Bourgeois discloses a retractable cover which employs a first embodiment utilizing the accordion fold method, whereby a generally "C" shaped channel positioned at the top of the side walls of a pickup truck is used to guide wheels connected to cross supports of flexible top material. In a second embodiment, a plurality of rigid top panels of progressively smaller dimension are designed to telescope successively one receivably into the other, with movement being enabled by utilization of the above mentioned "C" shaped channel and wheel combination in cooperation with a motorized mechanism.
In the prior art, there remains the problem of providing a cover for a storage facility, in particular a mobile vehicular facility, which is easy to operate, fully secure against the elements of weather and unauthorized entry, and substantially unaffected by environmental conditions that may cause debris to build up on the guides. Articulating covers are not easy to use, as mentioned above. Prior art retractable covers are subject to environmental conditions, particularly sand, dirt, or ice which can get into the "U" or "C" shaped channels used to guide reciprocation, causing impaired operability until the inhibiting conditions are removed. Accordingly, a retractable cover is needed which is substantially immune to these factors, and which yet provides a secure, easy to use covering for a storage facility, in particular those pertaining to truck cargo beds.